Results of on-pump and off-pump coronary artery bypass graft surgery in 30 days: an analysis by propensity score matching

Abstract

\n \n \n The results of coronary artery bypass graft surgery (CABG) performed with and without the support of cardiopulmonary bypass have already been widely discussed and studied, including through a few large randomized clinical trials. Despite the efforts, the findings of these studies still generate controversy and doubts about the outcomes achieved by the two techniques. One of the contested points is the heterogeneity of the degree of specialization in the off-pump technique in relation to the surgical groups that participated in the studies.\n \n \n \n To compare the results in 30 days of on-pump and off-pump CABG.\n \n \n \n A single centre cohort with 1,767 patients undergoing isolated CABG was initially evaluated (January 2013 – December 2018). 397 patients undergoing off-pump CABG and 1,370 patients undergoing on-pump surgery were identified. To obtain two completely homogeneous study groups, a propensity score matching was applied. For this, a logistic regression model was built with the variable use of CPB support as dependent variable. In the group of independent variables, 14 baseline and operative characteristics were included. The probabilities generated for each patient were used as scores to establish the match. To establish a pair, it was necessary to have three squares after the comma, with the fourth decimal place being the tiebreaker criterion in the pairing. In this way it was possible to obtain 332 pairs (N=664). The paired groups, on and off-pump, were compared by descriptive and univariate analysis and later a logistic regression model was applied to identify possible risk predictors and to verify the impact of CPB support on 30-day mortality. The level of significance was 5% and the analysis was performed using Python 3.0.\n \n \n \n None of the 29 baseline and operative characteristics showed a significant difference between the groups, demonstrating a high degree of homogeneity obtained from the propensity score matching, which enabled a solid comparison between the incidences of outcomes in 30 days. None of the analysed outcomes showed any difference between the groups on and off-pump, including AMI, stroke, major reoperation and death (1.5% vs 2.4%; p=0.401). Through regression analysis it was possible to establish that the use of CPB was not an independent predictor of risk for the occurrence of death (p=0.246).\n \n \n \n After matching by propensity score, patients who underwent surgery with and without CPB had similar incidences of 30-day mortality. In addition, it was possible to verify that the use of CPB was not an independent predictor of risk for the occurrence of death in 30 days.\n \n \n \n Type of funding sources: None. Propensity score adjustment by group 30-day outcomes vs CABG technique\n